Specimens of cervico-radicular bacterial mats are being obtained from persons with and without periodontal lesions. Samples are examined by phase-contrast microscopy, and assessed by fluorescent antibody techniques and cultural methods for suspected pathogens. Patients with lesions are being advised to use salts for their home-care oral-hygiene program and to take tetracycline hydrochloride if they are unable to eliminate white blood cells and motile bacteria from lesions. The response of salt and osseous tissues is being followed around teeth whose cervico-radicular spaces have been cleared of motile bacteria and white blood cells.